Rhesus macaques contain a unique cytomegalovirus (RhCMV). Our main goal is to investigate mechanisms of viral pathogenesis and antiviral immunity in RhCMV-infected macaques. Objectives are to (1) clone and characterize key portions of the RhCMV genome, (2) prepare essential reagents, (3) examine the virus-host relationship in fetuses, neonates, and juvenile/adult macaques, and (4) test anti-CMV vaccines based on viral proteins produced in genetically engineered microorganisms. In previous studies, the entire immediate early (IE1 and IE2) region of the viral genome was cloned and sequenced. More recently, glycoprotein-B (gB) and 65 kiloDalton phosphoprotein (pp65) were cloned and sequenced. Computer algorithms comparing HCMV and RhCMV show regions of high sequence conservation as well as regions of diversity. A detailed analysis of the transcription patterns for IE and gB genes has been conducted. IE genes have been expressed in bacterial vectors; these recombinant viral proteins will be used to produce monospecific antibodies for immunohistochemistry studies in RhCMV-infected macaques. gB and pp65 genes are being cloned into bacterial and mammalian expression vectors to produce viral proteins for immunization. In related studies, conditions have been optimized for detection of RhCMV DNA by polymerase chain reaction (PCR); this method will be used to monitor tissue and organ distribution of virus in naturally infected and experimentally inoculated macaques. A serosurvey has been conducted on 80 juvenile macaques (4-5 months); one seropositive animal was necropsied and the tissues have been examined for viral distribution and viral load. The virus was detected in 23 tissues analyzed, most notably in the salivary glands and kidneys. This research has produced cloned RhCMV genes and proteins for immunization, established assays for detection of virus and anti-viral antibodies, and described the in vivo distribution of virus in naturally infected macaques.